We demonstrated that exposure of organs into high-pressure CO and O2-mixed gas without immersion in stock solution leads to the maximum cell-protective effects of gas for preservation. This result is important to show the scientific evidenceand apply for clinical cases. In addition, we succeeded in rat limb preservation for one-week by using high-pressure CO and O2-mixed gas. The result indicates that high-pressure CO and O2-mixed gas is widely useful to organ preservation.